Insular Annapolis

Occasionally since coming to Annapolis, I've run into people who haven't been exposed to much.  That's the only way I can describe it.  Once it was someone who had never heard of hummus and never tasted olive oil or lamb.  I can understand the hummus, even though it is in most normal groceries now, it wasn't commonly available everywhere until recently.  The other two though, they seem so normal to me, such common ingredients that it's hard to imagine never even tasting them in a life of eating.  I've met several people like this, and I've just figured that everyone has different norms, big country, etc.  Especially easy explanation since there are lots of foods my big city friends and relatives think are normal and I won't touch (pickled herring, followed by the even more abominable herring in cream?).  I've also met Annapolitans who have never visited Baltimore or DC.  Major cities less than 30 miles away, with large numbers of cultural attractions, never visited.  OK, I can see it (with some difficulty).  Today however, I met a woman who told me she never knew a car could be rented until she was hired by the car rental company.  This I do not understand.  How do you watch tv or listen to the radio or talk to friends who've gone on vacation or read a magazine and not realize that cars can be rented?  I've been trying to bend my mind around it and I just can't get there.  Can anyone explain this to me?